Balloon catheters have been used for a number of medical applications. A balloon catheter comprises a balloon which can be brought from the deflated state into the expanded state by the introduction of a fluid, and from the expanded state back into the deflated state by evacuation. The fluid may be comprised of a gas or a liquid.
Balloon catheters are, for instance, used for the balloon dilatation of constricted blood vessels in the context of a percutaneous transluminal angioplasty. In that case, a balloon attached to a vascular catheter is advanced within a blood vessel as far a to a pathologically constricted vascular site, and the balloon is deployed on the constricted site under a high pressure (6 to 20 bar). This causes the constrictions, which are primarily due to arteriosclerotic vascular sclerosis, to be dilated until they will no longer, or less strongly, impair the blood flow.
Balloon catheters may, however, also be employed in the context of a pressure-controlled intermittent occlusion of a body vessel and, in particular, the coronary sinus. Methods for the pressure-controlled intermittent occlusion of the coronary sinus are, for instance, described in the documents EP 609914 A1, EP 230996 A2, EP 1406683 A2, EP 1753483 A1, EP 1755702 A1 and WO 2008/064387 A1. In those methods, the coronary sinus is cyclically occluded and released again by using a balloon, the occlusion of the coronary sinus, during the occlusion phases, inducing a pressure increase and hence a retroperfusion of blood via the respective vein into the nutritive capillaries of the ischemic region so as to enable a redistribution of flow into those regions. Upon release of the occlusion, the retroperfused blood is flushed out while metabolic waste products are, at the same time, discharged. The pressure in the occluded coronary sinus is each measured during the occlusion phases, the release of the occlusion as well as the initiation of the occlusion occurring as a function of the measured pressure values.
As opposed to a balloon dilatation in the context of a percutaneous transluminal angioplasty, the pressure-controlled intermittent occlusion of a blood vessel and, in particular, the coronary sinus does not aim to inflate the balloon with such a high pressure as to cause an irreversible deformation and, in particular, expansion of the respective vascular region. The inflation of the balloon rather is to be controlled in a manner that the balloon exerts a pressure on the vessel wall, which will just do to occlude the blood vessel to a sufficiently safe extent and prevent blood from flowing past the balloon. If too high a pressure is fed to the balloon, this will cause too strong a radial expansion of the blood vessel, whereby the respective mechanical load on the vessel wall may lead to irreversible damage, which is to be prevented anyhow. On the other hand, too small a pressure supply to the balloon would save the vessel wall, yet the balloon would not completely occlude the vessel.